Various utility companies typically place the appropriate utility supply line underground. This is for the convenience and safety of surrounding communities. In particular, in the natural gas industry numerous pipes extend from a supply system and extend throughout the communities to feed individual homes and businesses with a continuous supply of natural gas.
However, while placing supply lines underground protects the surrounding communities, the lines are then subjected to environmental conditions, such as moisture, temperature changes, ground shifting and otherwise, that could shorten the life of the pipe. Furthermore these pipes may be further damaged during alteration or repair of the same.
In response to these damaging conditions, the natural gas industry utilizes pipe that is precoated. Such coatings are well known in the industry of underground natural gas utilities. For example, such coatings (either commonly installed or commonly found) may include fusion bonded epoxies, extruded polyethylene, coal tar enamel, asphalt enamel and combinations thereof or the like. Preferred coatings by name include 3M™ Scotchkote™, Dupont NAP-GARD®, and ShawCor (Canusa-CPS).
However, it should be appreciated that the pipe portions or otherwise may inherently comprise of a protective coating. For example, in one aspect the protective coating may comprise of the exterior surface that has undergone oxidation. In such an occurrence, the material located below the oxidized exterior layer is at least partially protected from further oxidation.
One challenge the natural gas industry in particular encounters is the need to remove a portion of coating in order to weld a lead attachment wire. This would be necessary in order to cathodically protect the pipe. Cathodic protection is a system for preventing metal pipes from corroding. There are two types of systems for cathodic protection: 1) sacrificial anode, and 2) impressed current.
Sacrificial anodes can be attached to coated steel for corrosion protection sacrificial anodes are pieces of metal more electrically active than the steel pipe surface. Because these anodes are more active, the corrosive current will exit from the anode rather than the pipe. Thus, the pipe is protected while the attached anode is “sacrificed.” Depleted anodes must be replaced for continued corrosion protection of the pipe.
An impressed current system uses a rectifier to convert alternating current to direct current. This current is sent through an insulated wire to the anodes, which are special metal bars buried in the soil near the pipe. The current then flows through the soil to the pipe, and returns to the rectifier through an insulated wire attached to the pipe. The pipe is protected because the current going to the pipe overcomes the corrosion-causing current normally flowing away from it.
Both systems require that a lead attachment be welded to the pipe surface (often called a cadmium weld or “cadweld”). This cadweld can be achieved utilizing any metal to metal connection technique such as electrical, exothermic, acetylene, brazing, soldering or screw connection). Unfortunately, once a portion of the coating is removed for a cadweld or otherwise, a holiday is formed, thereby exposing the pipe to the surrounding environment and potential corrosion.
The industry has attempted to cover these holidays by providing a rubberized patch having a small area of centralized material, for protecting the weld, surrounded by an adhesive. However, the application of a small centralized material via a protective cap may not effectively cover holidays typically formed by the cadweld, especially those holidays that extend beyond the weld. Furthermore, the surface preparation required for adhesion of the rubber patch is extensive since dirt, corrosion and uneven or non-smooth surfaces hinders the patches ability to form a seal about the cadweld or holiday. As such, these patches often require the use of motorized abrasion tools to smooth and clean the surface prior to application. This is particularly difficult if the pipe portion is located substantially below ground and only accessible through a small hole. In this situation, the repairperson may not accurately place the small patch over the weld and the attachment wire.
To make things more difficult, it is becoming more common for utility repairpersons, or the like, of natural gas companies to use keyhole technology for reaching these underground pipe portions. Prior to keyhole technology, the conventional pipe repair practice consisted of making excavations to pipe that measured at least three feet by four feet across and six or more feet deep. Keyhole technology is the accessing of underground pipe and fittings by creating small (from 12 to 18 inch diameter) holes that are substantially vertical over these pipe portions. Coring tools and vacuum excavation equipment are typically utilized in the process. Typically, these holes are small, wherein a person would not normally be able to access the underground pipes without the use of specialized tools designed for the purpose of working on a pipe or fixture from a distance of six feet or more. Because Any repairs or modification to the gas lines must be done through these keyholes, often using keyhole tools, the ability of a repairperson or the like to use common tools in preparing surfaces for patching and applying patches is severely limited.
As such, there is a need for a method, device and tools adapted for sufficiently covering and protecting members such as cadmium welds, holidays or the like from the surrounding environment conditions, even when the surface of the pipe is less then perfectly clean and/or smooth. Still further, there is a need to accomplish the above task while using keyhole technology.